Meta-analysis: Diagnostic Performance of Low-Radiation-Dose Coronary Computed Tomography Angiography

OBJECTIVES: A new radiation dose-saving technique for noninvasive coronary artery imaging with computed tomography (CT) is available. The purpose of this study is to summarize current evidence about the ability of low-dose coronary CT angiography to rule out coronary artery disease (CAD) in symptomatic adults.

METHODS: Online databases, including MEDLINE, EMBASE, and the Cochrane Library, from inception through 31 October 2010; abstract databases; gray literature; reference lists of identified articles; and experts. No language restrictions were applied.  All investigators screened and selected studies that compared prospective electrocardiography-gated coronary CT angiography with catheter coronary angiography (the reference standard) in symptomatic patients with suspected CAD. Two investigators independently extracted patient and study protocol characteristics and rated methodological quality; differences were resolved by consensus or by a third reader. Multivariate random-effects models were used to obtain pooled estimates.

RESULTS: 16 studies, comprising 960 patients, were found (7 studies of single-source, 64-slice CT; 4 of dual-source, 64-slice CT; 2 of single-source, 320-slice CT; 1 dual-source, 128-slice CT; 1 of single-source, 128-slice CT; and 1 of single-source, 256-slice CT). On average, 2.4% of the coronary arterial segments were of nondiagnostic image quality, and 1 or more segments were nondiagnostic in 9.5% of the patients. The patient-level sensitivity and specificity of CT angiography were 1.00 (95% CI, 0.98 to 1.00) and 0.89 (CI, 0.85 to 0.92), respectively. The pooled vessel- and segment-level estimates showed lower sensitivity and higher specificity than the patient-level estimates. Statistically significant heterogeneity was found between studies for vessel- and segment-level estimates, which seemed to

be associated with body mass index and prevalence of CAD but not with CT scanner characteristics. The small number of studies, half of which were from a single tertiary center, limits generalizability. The potential harms of the imaging tests were not well-evaluated.

CONCLUSIONS: Early evidence suggests that low-dose coronary CT angiography matches the sensitivity of catheter-based angiography, has low radiation exposure, and is a potentially valid alternative to catheter angiography for triaging symptomatic patients with a clinical suspicion of CAD.

PMID: 21403076

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